Investigation of wheel-rail forces at short-wave rail surface defects, based on the example of welded rail joints

Short-wave geometric defects on the rail surface increase the dynamic excitation of the vehicle-rail system, resulting in more severe ballast degradation and higher maintenance costs. This paper examines the impact of vehicle and track parameters on wheel-rail forces when passing over short-wave defects, using rail joints as an example. Measured geometries of welded joints are used as input for a multi-body simulation model. The model is validated with measured axle box accelerations, resulting in a reliable simulation model for further investigations. The historical shift from bolted to welded rail joints has reduced dynamic wheel-rail forces. Simulations demonstrate the effects of the various rail surface geometries. In the literature and practice, analytical approaches are often used to determine the dynamic wheel-rail force at dipped joints. These are compared with simulation results to demonstrate applicability and limitations. Furthermore, the study shows the significant potential of rail pads in comparison to the influence of the unsprung mass on the vehicle side.